Hypodermic syringe



May l, 1923. 1,453,418

J. A. TESSMER.

1 HYPODERMIC SYRINGE Fild oct. 22, 1920 atented May l, 1923.

' UNiTED sra ATENT oFFlcE.

JOHN A. TESSMER, F WORCESTER, MIASSACHUSETTS.`

HYPODERMIC SYRINGE.

Application filed October 22, 1920. Serial No. 418,672.

To'aZZ whom-it may concern.'

Be it known that I, JOHN A. TnssMnR, a citizen ofv the United States, residing at yvorcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Hypodermic Syringe, of which the' following is a specification. This invention relates to'improvements in `hypoderrnic syringes as used in dental and surgical practice. It is the object of my invention to improve the construction of such syringes, making them, more effective and convenient in operation and better adapted y permits the syringe to be more readily filledl with injecting fiuid.

It is absolutely essential in the use of a hypodermic'lsyringe that no foreign matter shallv enter the needle or be` carried along with the injecting fluid. For this reason ordinary methods of packing the piston to prevent leakage are unsatisfactory.

An' importantffeature of my invention relates to the provision of an improved piston construction by which the use of packing (as commonly understood) is entirely avoided, while at the same time4 leakage past the piston is effectively prevented.

As shown herein the piston is formed as a cylindrical metal rod of uniform crosssection and is provided with a'series of parallel circumferential grooves. The piston is preferably provided with a thin coating or layer of a softer metal such as gold, whichwill permit ajcloser vfit and an easier sliding movement ofthe piston. j

My invention further relates to arrangements and combinationsof parts which will be hereinafter described and more particularly pointed out in the appended claims.

-v A preferred form of my invention vis shownA in the drawings in which- F ig. 1 is a sectional side elevation of my improved syringe Fig. 2 is an enlarged sectional side elevation showing certain of the parts in spaced relation; l f

Fig. 3 is a side view of' thesyringe cas tFig. 4; is an end view of the clamping nut, looking in the direction of the arrow 4 in Fig. 2; f

Fig. 5 is an end view of the handle;

Figs. 6 and 7 are side and end views ofv the needle and its enlarged head; and

Fig. 8 is a perspective view of aportion of the plunger or piston.

Referring to the drawings, I have shown a syringe comprising a casing 10, a cylinder or sleeve 1l, a needle 12having an enlarged head 13, and a piston 14.

The needle 12 is of a usual type and. is firmly secured in the enlarged head 13 which is preferably of a relatively soft metal.

The outer surfacel of the head 13 yis of the 10. When the nut is screwed firmly on the casing, the sleeve 11 is clamped therein and is firmlyseated against thev needle `head 13. j

A handle 17 is loosely mounted on the casing 10, and is positioned thereon by the projection 18 (Fig. 2). j The handle is pro,- videdv 4with notches or recesses 19 fitting lugs 20 on the nut 16. When the handle is in' the position shown in Fig. 2, 'itis freely rotatable relative to all other parts of the syringe. vWhen fmoved to the position shown inFig. 1, the recesses 19 receive the projections 20 and the handle maybe used as awrench to tightenthe nut. 16 against the end of the cylinder 11.

The outer portion 21 of the ,nut 1.6 is preferably bell-shaped, as shown in the drawings. and this, feature is found to be of material .K

advantage when it is desirable to iill the cylinder by pouring the injecting fluid directly into the cylinder instead of drawing it in through the, needle 12.

The piston 14 is formed of relatively hard material and of substantially uniform crosssection throughout its length, steel or other suitable metal being' commonly used, and `is provided with a suitable handle 22.1at its outer end. The piston 14 is a c-los'e sliding lit in the cylinder 11 and,isprovidedwith a series of parallel circumferential grooves 23, preferably extending., throughout the whole working portion of ,thepisvton Thesey grooves.y areof Lrelatively* small dimensions and have abrupt, sharp edgeswhere .they meetthe cylindrical1 surface of .the piston.

I find .it desirable: Vto provide-the finished piston with a very thin coating of a softer metal, which,vll may abe conveniently accomplished by electroplating the piston with `a very thin ,deposit of gold, orothermetal, thedeposit being, so extremely thinthat it is impossible to indicate it in the drawings. This thin, layer, however, being',I of much softenmetal, makes possible, a closeriit of .the piston in lthe cylinder andasmoother sliding movementthereof, and in fact acts to a certain extent similar to alubrcant.:

Havingkfdescribedthe details of construetionof my` improvedsyringehthe advantages thereofl vvill'rbe,` readily apparent. rlhe .re-7 enforcement ofthe needle by the relatively large head l13 of Asofter material greatlyref duces the breakagefof needleswhenv the device4 isin use. All partslof the syringe may be separated byremoving the single nut `16 andthe syringe may be readilyreassembledi without handling anyinternal surface `of the device, thus` avoiding thel possibility of infection. AThe handlefl? may ybe kturned to` any desired'angle when the device is inuse,

andfthusV constitutes4 an adjustable handle as well as a wrench for the nut 16.

The provision of the plurality rof grooves 23 inthe lpiston, 14 avoids ,the necessity of usingany ypacking between the piston and'Y thecylinder and .has a very important .ef-

fectin preventing leakage past the piston.r

Anyfliq'uid which succeedsinworking past the close fitting end of the piston 14 engages the 4sharp perpendicular wall of the first groove 23 Vand is directed intojthe groove withy a moreor less rotary motion. Any lof thesolution which may finally escapel from the iirst groove encounters similar resistance in the, second groove while yat the same time it is under reduced pressure as it is more remote `,from/the cylinder., As each succes# sive groove is encountered, the pressure, is further reduced while the resistance remains unchanged. Consequently, leakage past the piston i is substantially eliminated.

Having thusl described my invention, it will beevident that changes and modifications ycan be madevtherein by those skilled disclosed, but'what I claim isc-f.

in the art within the spirit and scope thereof as set forth in the claims and l do not wish to be otherwise limited tothe details herein 1. A hypodermic syringe having, in combination, a cylinder for thel injecting fluid, and a piston'slidable in said cylinder to force the fluid therefrom, said piston being formed as a metal rod of uniform cross-sectionI throughout its length and having a series `of parallel circumferential grooves formed in the cylindricalsurface thereoftopre. ventleakage of the, fluid past .saidgpiston, the cylindrical wearing surface lof said .pis ton beingcoated with a very thin` deposit of a soft metal kensuring,close'sliding fit of said parts.

2. A hypodermic ksyringe .comprising I a, casingmember having a substantiallyconi,- cal 1 outwardly contracted axial-l opening,y, w85 needle extending therethrough and.: having e. an enlarged head with ak substantially coni,-x` cal surface fitting` said axial openingnysaidw casing member, a seating. member. engagingg the inner and larger enol of saidv needle head, ,90 and means to move said seatingmember ,relaf tively-to saidgcasing member against saidf:y needle headv thereby exerting outvvaldffprese; sure on the inner and Alarger end` of ;said,fJ needle heady and firmlyseating-said needlehead` iny the substantiallyv conical ,axial open-,1 ing` of said casing member.y Y 1 3. A hypodermicv syringe compiffisingi;v al, casinghavingv a relatively fixed end- `with-2 a.: contracted opening therein, a needleextend.n 2100 ing through said openingv andghaving.an;-en-y larged head seated within said end, a sleeveslidable insa'id casing and abutting the'inL nerend of said needlehead, andy means ,to i. forcesaid sleeve firmly against saidhead -to105 secure said needle in said casing.`

4. A hypodermic syringe-comprising casing having a relatively fixed-.end :WitluagA contracted opening therein, a,needle extend,` i ing through said .opening and .having anyl 110 enlarged head seated within said ,end/,mayl sleeve slidable insaidgcasing andfabuttgingv the, inner end of said needlefhead and means` to force said sleeve firmly against'said head, to secure said needlein saidcasing, thel headff of said needleI being of relativelyfsoftqmate; f.. rial and said sleeve .having a thin hard edge; seating itself in said head when pressureis applied to saidvsleeve.

5. A hypodermic syringe comprising a 12,0 casing having a contracted end, va,.needl'e; having` an enlarged head fitting against-fthe linner face ofthe contracted. end of saidcas;

ing, a sleeve slidable insaid casing and abut;- e

tingsaid needle head and a nutfgthreadedfgle ing an enlarged head fitting against the inner face of the contracted end of said casing, a sleeve slidable in said casing and abutting said needle head, and a nut threaded Vto said casing and effective to force said sleeve against said head, thereby seating the needle firmly in said casing, said nut being flanged outwardly to provide a bell-shaped mouth for said syringe.

7. A hypodermic syringe comprising a casing, a needle having an enlarged head fitting the end of said casing, a cylindrical sleeve in said casing, a nut threaded on said casing and engaging said cylindrical sleeve, and a handle loose on said casing, said nut and said handle having co-operating portions by which said nut may be turned by said handle When said portions are engaged.

8. A hypodermic syringe comprising a casing having an end with a conical inner surface and With a contracted central opening, a needle extending through said opening and having an enlarged head with a conical surface engaging said end, a sleeve slidable in said casing and abutting the head of said needle, and means to force said sleeve against said head to seat the head iirmly in Said casing.

In testimony whereof I have hereunto affixed my signature.

JOHN A. TESSMER. 

